Implantable micro-textured scar inducing ePTFE structures

ABSTRACT

Bio-implantable textured tubular and sheet structures of un-sintered ePTFE are described. Such micro-textured structures stimulate robust development of beneficial bio-integrative scar attachment to adnexal soft tissues. Methods for texturing one side of an un-sintered extruded ePTFE tube or sheet are also described. A select length of tubing of any thickness or diameter is applied over a matching mandrel and adhesively stabilized thereon by applying intense suction. The texture is made by “RIGDA tooling” into the wall thickness of the material and by removing undesired material by distraction and avulsion tooling and methods assisted by vibration, leaving intact the finished product. Disclosed is an implantable, non-attached, enveloping, conforming and supportive drainage cover for breast and other soft implants. The drainage cover has numerous through and through cut lucencies which allow for liberal ingress and egress of interstitial biologic fluids enabling efficient drainage postoperatively, especially under the influence of active wound suction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/408,453, filed Oct. 29, 2010, the contents of which areincorporated by reference herein in their entirety as if fully set forthherein.

RELATED APPLICATIONS STATEMENT

This application is related in subject matter to my prior patentsincluding: U.S. Pat. No. 4,955,907 (Apr. 11, 1990), U.S. Pat. No.5,282,856 (Feb. 1, 1994), U.S. Pat. No. 5,462,781 (Oct. 31, 1995), U.S.Pat. No. 5,653,755 (Aug. 5, 1997), U.S. Pat. No. 5,779,734 (Jul. 14,1998), U.S. Pat. No. 4,187,390 (Feb. 5, 1980), U.S. Pat. No. 6,921,418(Jul. 26, 2005), U.S. Pat. No. 7,041,127 (May 9, 2006), and U.S. Pat.No. 7,273,493 (Sep. 25, 2007), which are hereby expressly incorporatedby reference in their entirety. No claim of priority is made to any ofthese prior patents.

FIELD OF THE INVENTION

The present inventions related to improved biocompatible implants, andmethods for their manufacture, for use in the body. In particular, theinventions relate to improved biocompatible implants having enhancedtissue in-growth properties. In another aspect, the present inventionrelates to an implantable enabling device for breast augmentative andreconstructive surgery in particular and to surgical wound drainage carein general.

BACKGROUND OF THE INVENTION

A textured dual-sided sheet of ePTFE, as in my U.S. Pat. Nos. 5,282,856and 6,921,418, has multiple uses as an implant in surgicalreconstruction of the body. It has applicability as a fitted coveringfor space-occupying implants that require isolation and stabilizationsuch as implanted infusion pumps, orthopedic devices, electronic devicessuch as defibrillators, glucose meters, pacemakers, and others. It alsofinds applicability as a hernia repair material, as a safehypoallergenic dura mater replacement material, as supportive coveringsfor soft organs such as kidney, pancreas, liver or spleen, for example.It is also useful as a protective support and drainage cover for breastand other soft implants. Additionally, it is useful as a repair materialfor wall of thorax, ruptured diaphragm, pericardium, and so forth.

Used as an implanted covering, the textured dual-sided ePTFE sheetstructure is very useful for its ability to induce bio-integrative scaron its textured surface, thus enabling it to become quickly andpermanently attached to adjacent bodily structures. A textureddual-sided ePTFE tubular structure is another useful implantablestructure that benefits from the ability to bio-integrate with the body.Drugs, transplanted live tissues in their nutrient media including:pancreatic beta cells, bone marrow, stem cells, and others containedwithin such a textured sheet or tubular repository structure can serveas in situ reservoirs upon healing.

Bio-integration implies an intense adherence between an implantedmaterial and the body, which can help defeat potential complications ofsurgery such as de-lamination, dehiscence and seroma fluid accumulation.The avidity of bio-integrative scar attachment is principallycharacterized as the amount of force required to physically separate thetubular ePTFE structure from attached soft tissue under standardizedtest conditions.

Whereas smooth ePTFE surfaces with porosities in the 1-2 micron rangeare used to prevent adherence to bodily structures, the purpose ofmicro-textured ePTFE is to do the opposite—to induce targetedbio-integrative scar and adherence. Creating both smooth andmicro-textured surfaces on the same implantable ePTFE structure is amanufacturing challenge. Crafting both surfaces on a tubular ePTFEstructure adds another degree of complexity. In order to attractfibroblasts, textured ePTFE surfaces must be free of oxidizedby-products and other surface contaminants such as manufacturing debris,glazing, or extrusion impressions.

According to Goldfarb (U.S. Pat. No. 6,436,135), by providing theappropriate wall thickness of the textured tubular structure, as well asby creating through and through holes or slits of optimal diameter anddensity, a highly desirable neo-intima cell layer can be encouraged andsupported with capillary in-growth into the lumen. It discloses aprosthetic vascular device formed from a small bore tube ofpolytetrafluoroethylene which has been heated, expanded and sintered soas to have a microscopic superstructure of uniformly distributed nodesinterconnected by fibrils and characterized by: (a) an averageinternodular distance which is (i) large enough to allow transmuralmigration of typical red cells and fibroblast, and (ii) small enough toinhibit both transmural blood flow at normal pressures and excessivetissue ingrowth; and (b) an average wall thickness which is (i) smallenough to provide proper mechanical conformity to adjacentcardiovascular structures, and (ii) large enough, when taken inconjunction with the associated internodular distance, to preventleakage and excess tissue ingrowth, to allow free and uniform transmuralnutrient flow, and to assure mechanical strength and ease ofimplantation.

According to Zukowski (U.S. Pat. No. 5,462,781) entitled “SurfaceModified Porous Expanded Polytetrafluoroethylene and Process forMaking”, an implantable porous expanded polytetrafluoroethylene materialhas a microstructure of nodes interconnected by fibrils and the surfaceof the material has been modified by the removal of fibrils from thesurface. The surface has the appearance of freestanding node portionsnot interconnected by fibrils but rather having open valleys disposedbetween the freestanding node portions. Unmodified material beneath thesurface maintains the original microstructure of nodes interconnected byfibrils. The modification is preferably done by exposing the surface toradio frequency gas plasma discharge with a reactive etching gas for alengthy amount of time such as about ten minutes. The depth of fibrilremoval from the surface is substantially a function of the duration andamount of energy applied to the surface.

According to Gore (U.S. Pat. No. 4,187,390) entitled “Porous productsand process therefore”, a tetrafluoroethylene polymer in a porous formhas an amorphous content exceeding about 5% and has a micro-structurecharacterized by nodes interconnected by fibrils. The material is saidto have high porosity and high strength. Shaped articles such as films,tubes, rods, and continuous filaments are contemplated. Laminations canbe employed and impregnation and bonding can be used.

Historically, severe scar contracture around a silicone breast implantwould harden and deform the entire breast, with consequences for bothpatient and surgeon. Multiple causes of scar contracture have beenidentified, including a ready supply of seroma fluid containing collagenmonomers, cellular debris, mediators of inflammation due to surgicalinjury, physical abrasion and exposure to allergenic materials likesilicone gel, and wound contaminants. In the case of wounds containingsoft implants, seroma fluid containing collagen monomers and admixedmediators of inflammation are problematic because such a combinationpromotes additive layers of scar. A large amount of fluid permits animplant to float in the wound space and allows for mechanical abrasionas it makes repeated abrasive contact with surrounding soft tissues, andthus can become a serious complication of surgery. So-called developing“capsular scar contractures” become thicker and more dense and grosslydistort an implant and surrounding breast tissue.

Over time, a number of partial solutions to the problem of scarcontractures have been tried including: (1) more cohesive gel fillersfor implants which are less likely to be allergenic and more likely toretain implant shape, (2) sub-muscular rather than sub-glandularplacement of implants, (3) non-allergenic fillers such as normal saline,(4) pressure adaptive implants, (5) fastidious surgical dissectiontechnique with frequent wound irrigation and suction, (6) use ofcortico-steroid injections into surrounding soft tissues, and (7)topography-modifying implant surfaces, as well as others.

However, significant esthetic problems of sub-optimal implant position,implant deformation and hardness remain for some patients, oftennecessitating re-operation plus installing a new set of implants.Implant motion and abrasion injury at the interface with soft tissueresults in accumulation of seroma fluid in the wound. Such seroma fluidaccumulation which contains cellular debris, mediators of inflammation,fibroblasts and collagen, remains an un-solved problem requiring asolution. Because it can persist for a prolonged period of time in awound space as an inflammatory material, it promotes the development ofmultiple layers of capsular scar. Such capsular scar can then undergosevere contraction to deform the entire breast.

SUMMARY OF THE INVENTION

In one aspect, the present invention is an “Implantable Textured TubularePTFE Structure”. The Method of Manufacture and preferred RIGDA Toolingfor making this textured tubular device are described and also claimed.

New and improved bio-implantable textured tubular and sheet structuresof un-sintered ePTFE are described. Such micro-textured structuresstimulate the robust development of beneficial bio-integrative scarattachment to adnexal soft tissues. When confronted with an invitingePTFE surface structure, fibroblasts are attracted to it and insinuatethemselves by diapedesis into available interstices and secrete liquidcollagen monomers within the “forest” of variegated villous remnants ofsubstrate ePTFE. Such deposited monomers of collagen, attract morefibroblasts and are substantively in non-parallel alignment due to thegreat complexity of the spaces into which they are secreted. Depositedmonomers of collagen subsequently “cement in place” by undergoingpolymerization and become deep anchorages for maturing scar tissue.Angiogenesis rapidly develops within such scar matrix accelerating itsdevelopment. Foundational scar adheres to a very complex pristinecrystalline surface with unusual tenacity and thus bio-integrates withthe ePTFE implant. The greater such surface area and the greater thecomplexity of such insinuating scar, the more avid the adherenceestablishing bio-integration. Trials of a variety of textures have shownthat optimal fibroblast in-growth, resulting in optimal bio-integrativescar development, is a function of a dense pristine and complexcrystalline topology featuring very numerous tattered and shreddedsurface villi.

In one aspect of the invention, an implantable tube for use in a body isprovided. The tube is an extruded ePTFE tube with a first inner surfaceand a second outer surface. The tube has a thickness dimension betweenthe first inner surface and the second outer surface. The second outersurface is textured to promote body tissue bio-integration into thesecond surface. Preferably, the second outer surface is textured by theprocess of releasably affixing the first inner surface to a worksurface, contacting an active rotary gouge to the second outer surfaceto remove material from the tube, at least including gouging material inthe thickness dimension from the second surface toward the firstsurface, thereby separating the gouged material from the tube, therebyforming an irregularly configured second outer surface, the outersurface having resultant irregular voids, and removing the gougedmaterial textured second surface. The gouged or avulsed material revealsa pristine avulsed crystalline exposed ePTFE surface. Textured surfacevoids of 2 to 20 microns in depth are preferred. Textured surface voidsof at least 15 microns, even deeper than 20 microns, are also preferred.

New and improved methods for texturing one side of an un-sinteredextruded ePTFE tube or sheet are also described. A select length oftubing of any thickness or diameter is applied over a matching mandreland adhesively stabilized thereon by applying sufficient suction to holdthe tube while being textured. The texture is made by “RIGDA tooling”into the wall thickness of the material and by removing undesiredmaterial by distraction and avulsion tooling and methods assisted byvibration, leaving intact the finished product. The RIGDA toolinginstrument may be a modified burr made of tool steel, a RIGDA disc madeof ceramic, diamond grit, or other suitable particulate abrasivematerial. The entire selected surface may be textured or a complextexture pattern may be applied. The ePTFE tubing as well as sheets maybe engineered utilizing any length, wall thickness, node and fibrilstructure, texture, voids, laminations or other features to suit. Sheetscan be micro-textured and otherwise structured to enhance their use as away to protect and support bodily tissues as well as in drainage ofseroma fluids. The applied micro-texture stimulates bio-integrative scarwhen implanted.

In one implementation of the methods for texturizing an implantable tubeor other structure, a surface being textured by the process uses thesteps of providing a mandrel sized to receive the inner surface of thetube, the mandrel having a plurality of holes to couple the innersurface of the tube to a vacuum space. The mandrel and tube arereleasably affixed by application of a vacuum to the vacuum space. Anactive rotary gouge contacts the second outer surface to remove materialfrom the tube, at least including gouging material in the thicknessdimension from the second surface toward the first surface, therebyseparating the gouged material from the tube, thus forming anirregularly configured second outer surface, the outer surface havingresultant irregular voids. Next, the gouged material is removed from thetextured second surface. Preferably, the rotary gouge and mandrel aremoved relative to one another. In one aspect, the rotary gouge may bemoved parallel to the axis of the tube. Alternately, the rotary gougemay be moved at any other angle relative to the axis of the tube,including perpendicular to the axis of the tube. Discontinuingapplication of the vacuum permits removal of the texturized tube fromthe mandrel.

The permanent fixation of such textured ePTFE structures in the body isfacilitated by the fact that favorable highly complex pristinecrystalline topology induces rapid growth of scar tissue into themicro-textured surface and thus makes bio-integration possible.Preferably, the bio-integration is adapted to occur at least 15 micronsin the thickness direction from the second outer surface.

Also, bonding and laminating will be greatly facilitated by RIGDATooling creation of a micro-texture surface on ePTFE tubing as well asother like structures. Adhesives bond much more successfully tomicro-textured ePTFE surfaces, representing greatly increased surfaceareas. RIGDA Tooling used as taught herein will likely be a usefulmethod for configuring many new medical devices.

Multiple manufacturing options can be brought to bear on texturedtubular ePTFE structure design. Generic textured tubular ePTFE can bemanufactured in a large variety of porosities manifested as node andfibril micro-structures, in extruded stock diameters, thicknesses andlengths. It can be customized for a variety of uses by heat welding,bonding, laminating, by tapering the tube in the lengthwise dimension,by cutting through-and-through holes or slits in the wall of thesetubes, and utilizing other manufacturing techniques. Further, it can beconfigured to serve as a repository for drugs which can be introducedinto the micro-structural voids within the tubular material by applyinginert gas pressure externally. The structure so infused with drug maythen be freeze-dried to extend the shelf life of the device/drugcombination. The tube can additionally be inverted on itself so that thetexture is manifested on its inner surface.

The desired texture which is created into the thickness dimension of theextruded ePTFE tube can be customized to satisfy unique engineeringspecifications (see FIGS. 3 and 4 etc.), particularly if the intendeduse is as a blood vessel prosthesis or graft.

The present invention is a soft supportive drainage cover for implantsthat is improved by at least two features: (1) the bio-integrativecharacter of the texture that is applied to the outward facing side of athin un-sintered ePTFE sheet, with the opposite side being smooth, plus(2) a high number of lucencies (used herein in the context of holes,slits, or other passageways) cut through the drainage cover to permitinterstitial fluid to enter and to be drained effectively, and to permitthe cover to adaptively conform to a given implant shape.

In yet another aspect of the inventions, an implantable, non-attached,enveloping, conforming and supportive drainage cover for breast andother soft implants is provided. It is an improvement over prior art inthat it helps deal with implant motion, seroma fluid accumulation, andhelps to minimize excess scar in a wound. It is a bi-lobed ePTFEsheet-like cover that has two distinct surfaces. It has a uniquebio-integrative texture on the side directly facing the body softtissues, that is—away from the implant itself, and a smooth surface onthe opposite side facing toward the implant. The micro-texture whichinduces scar attachment to soft tissues is made by a unique RIGDAProcess. The drainage cover has numerous through and through cutlucencies which allow for liberal ingress and egress of interstitialbiologic fluids enabling efficient drainage postoperatively, especiallyunder the influence of active wound suction. Furthermore, it severelylimits shear motion at the soft tissue-drainage cover interface acutely,provides for long-term structural support of bio-integrated breasttissue, and protects against capsular contracture.

The invented drainage cover is a significant advance over prior artbecause it confronts the problems of the prior art directly. Themicro-textured multi-lucent drainage cover described herein enablesbreast tissue to be sucked down into intimate contact with the drainagecover. This enables bio-integration of the cover thus minimizing shearmotion of the implant, and also allows for the effective drainage ofseroma fluid. The reduction of motion at the soft tissue-breastprosthesis interface, along with improved drainage of seroma fluid aresignificant solutions to some of the aforementioned problems.

In one implementation of the seroma drainage device for use in a body, afirst ePTFE sheet has a first surface and a second surface. The secondsurface is textured to promote body tissue bio-integration into thesecond surface. Preferably, the second outer surface is textured by theprocess of releasably affixing the first inner surface to a worksurface, contacting an active rotary gouge to the second outer surfaceto remove material from the tube, at least including gouging material inthe thickness dimension from the second surface toward the firstsurface, thereby separating the gouged material from the tube, therebyforming an irregularly configured second outer surface, the outersurface having resultant irregular voids, and removing the gougedmaterial textured second surface. A plurality of lucencies are disposedbetween the first surface and the second surface, the lucencies beingadapted to permit the flow of fluids within the body from the firstsurface to the second surface.

Seroma fluid normally accumulates in a surgical wound as the result oftissue injury and contains many inflammatory mediator substances,collagen monomers and blood components. If not expeditiously eliminated,seroma fluid can result in chronic abrasion, more inflammation,excessive scar deposition, more seroma production and deforming capsularcontractures.

External pressure dressings and closed suction are used to initiateperi-implant wound drainage after surgery. However, the surgeon needs away to prolong the efficient suctioning of the peri-implant space untilthe wound is more advanced in the healing process. Blood clot canobstruct the suction system and cause a drain to fail. Wound suctioningneeds to begin early and to be sustained for a period of time. Thelucencies created in the invented cover help to mobilize seroma fluidquickly and help to sustain suction allowing for sufficient contact timebetween soft tissues and the cover to bio-integrate properly. Frictionand abrasion are thereby minimized and breast tissue is supported.

The described cover adheres to enveloping breast tissue bybio-integrating with it. A pristine crystalline and complex ePTFEsurface is a requirement for the texture that serves to induce“bio-integrative scar”. The bio-integrative process begins whenfibroblasts are attracted to the pristine complex crystalline surfacewhose method of texture manufacture is described earlier and pertainsherein again in full. Insinuated fibroblasts get situated within thetextured surface and secrete collagen monomers which then polymerize.

As polymerization of collagen proceeds, scar is incorporated into andonto the complex topography of the hyper-convoluted surface. It adheresintensely to the ePTFE sheet and thereby grossly reduces or eliminatesshear motion at the soft tissue interface with the cover.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a semi-schematic top view of a preferred embodiment of thepreferred apparatus for creating the texture into the thicknessdimension of dual-sided tubular ePTFE.

FIG. 2 clarifies relational detail in an exploded magnifiedsemi-schematic top view of the spindle-mandrel apparatus of thepreferred embodiment depicted in FIG. 1.

FIGS. 3A-D depict examples of furrow patterns of texture that can becreated into the wall thickness of an ePTFE tubular structure with theapparatus in FIGS. 1 and 2.

FIG. 3E depicts a textured tubular repository which may be used forlocalizing donor cells, radioactive isotope labeled drugs or othermaterials to internal bodily structures.

FIGS. 4A and 4B depict a prototypical scheme for efficient laser cuttingof access holes through the wall of textured tubing.

FIGS. 5A and 5B depict texture applied both internal and external to atextured tubular ePTFE repository.

FIG. 6 depicts a prototypical preferred embodiment “Rotary Impaling,Gouging, Distracting, Avulsing Tool”—or “RIGDA Tool”.

FIG. 7 depicts a custom fitted Drainage Cover surrounding a prototypicalbreast implant.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, the hollow spindle/mandrel assembly 1 ismounted on a lathe which has a computer-controlled variable speed drive2 and including “forward and reverse”. Programmable rotating andreciprocating motions of the lathe advance the spindle/mandrel assembly1 into position with respect to the compound motion “RIGDA ToolAssembly” 3, which is made to transition along three axes 4independently. All feed motions are made programmable on the machine. Avacuum source is fitted to the machine. It should be noted that FIGS. 1and 2 are concept drawings and thus are semi-schematic. As would beappreciated by a person skilled in the art, actual manufacturingdrawings very likely would appear different.

The spindle-mandrel 1 is comprised of a solid high grade stainless steeltank, other structural materials, an adaptive coupling consisting of anintegrated hollow conical electromagnetically actuated, and keyed socketchuck 5 which receives the standard precision fit stainless steelconical bases of interchangeable mandrels. 6 Mandrel portions withconical bases are essentially tubular elements designed to adhere toePTFE substrate material.

Mandrels may be manufactured in any length and diameter to suitparticular applications. The stainless steel tubular portion of eachmandrel is multiply perforated 7 by “e.d.m.” (“electrical dischargemachined”) or “laser-drilled” holes which permit vacuum-adherencestabilization of tubular ePTFE mounted thereon. The perforated endportion of the mandrel is made blunt and sealed by swaging and welding 8or equivalent methods.

A segment of extruded tubular ePTFE is mounted on the selected mandrelmanually in a “clean room” and affixed thereto by applying a vacuumpreferably in an amount sufficient to hold the work piece in placeduring the texturizing operation, most preferably an intense vacuumthrough the mandrel 9. The programmed RIGDA tool creation of themicro-texture (see below) into the thickness dimension of the tubingwall 10 then proceeds with vacuum adherence stabilization of the tubularePTFE substrate and with all requisite motions of the RIGDA tool. In onepreferred embodiment, “RIGDA-tooling” is performed by at least one RIGDAtool 11 rotating at approximately 2,000-6,000 rpm with the proximity andattitude of the selected RIGDA tool under micrometer adjustment control14.

Vacuum adherence is achieved by collapsing the space 16 between theePTFE tubing substrate and the perforated hollow mandrel. Vacuum isapplied through the rotating aspiration coupling 17 located at thenon-mandrel end, with the intensity of vacuum automatically controlledand brought to bear at the perforated portion of the mandrel. Vacuumspace 18 is continuous through the entire spindle-mandrel. As appliedvia perforations through mandrel 7, the vacuum is made sufficientlyintense so as to optimize the purchase caused by the edges of thoseperforations acting on ePTFE tubing, thereby firmly holding the tubingconcentrically on the mandrel to ensure that there be no slippagewhatsoever.

The tubular portion of the mandrel may additionally be splined 15 toassist in preventing slippage. The porous nature of the ePTFE substratewill allow for spontaneous gradual loss of vacuum asthe—“rotary-impaling-gouging-distracting—avulsing—RIGDA process” takesplace, therefore it is highly desirable to automatically re-establishsufficient vacuum to maintain good adherence.

Particulate ePTFE is scavenged by a dedicated vacuum system. Engineeringspecifications dictate relative motion of spindle-mandrel assembly 1,and electrically powered RIGDA Tool assembly 3. Pressurized nitrogen gas19 is used to unclog RIGDA tools of ePTFE substrate chaff as well as tocool the tooling. Texture and surface topology will vary with selected“rotary tooling speed”, tube wall thickness, tooling gouge design, angleand depth of tooling, substrate thickness, node and fibrilmicro-structure, and other variables. There will be a direct correlationbetween friction created by tooling action and the texture of thecreated micro-villi.

The optimal textured surface enabling bio-integration is achieved whenthe featured “RIGDA tooling process” applied to substrate tubular ePTFEmaterial results in a micro-texture that is crystalline and pristine inquality and structurally sufficiently complex so that fibroblasts areinduced to move into and onto the prepared surface. Such a surfacetopology consists of a complex of exposed tattered-frayed crystallinevillous structural remnants of ePTFE and spatial voids which are verynumerous in the 2.0-20.0 micron range 13. The larger such complexpristine surface area is, the greater the adherence of attractedfibroblasts and ultimately bio-integrative scar.

Removal of finished product is assisted by complete reversal of vacuumfollowed by switching off electrical current in the electromagneticsocket chuck lock 5.

The “RIGDA TOOLING process” requires the introduction of an activerotary gouge (see FIG. 6) which gets aggressive purchase on/into theePTFE material by “impaling” and “gouging” it. Upon “applying hightorque rotary force”, there is efficient “tearing” and “distracting” ofthe material at the crystalline level which continues until there issudden “release-avulsion” of a variable amount of base material—leavingan irregularly configured remnant of substrate material and resultantirregular void. As shown in FIG. 6, multiple, such as 10 or more,vertical cutting teeth are provided. Each tooth projects outward fromthe center of the tool. A common shaft connects to the drive.Preferably, the teeth include gouges or divots to aid in the RIGDAprocess. Optionally, a grinding wheel may be used to form the gouge ordivots.

Tooling furrow pattern, depth of tooling process, and substratethickness are engineering specifications developed particularly for agiven product. The dynamic nature of the RIGDA tooling process resultsin an “additional component of vibration inherent in the process due tosudden release of the tooling followed by the abrupt re-capture ofadditional substrate”, resulting in ever greater variability of shapeand length of shredded remnant villi and therefore of overall surfacetexture. FIGS. 3 A to E show optional patterns, such as (A) across-hatch, (B) parallel diagonal stripes, (C) complex hexagons orportions thereof, (D) linear stripes parallel to the axis of the tube,and (E) cross-hatched with interpositioned regions.

FIG. 3E depicts a textured tubular repository which may be used forlocalizing donor cells, radioactive isotope labeled drugs or othermaterials to internal bodily structures including organs such as theliver, lung, parietal pleura, spleen, pancreas, intestines, pelvicfloor, retroperitoneal space, bone marrow and others. Minimal incisionendoscopic techniques may be utilized. When implanted adjacent totargeted tissues that require a substantial drug treatment over time, atextured tubular repository may be configured to have a subcutaneousinjection reservoir connected by a tube which would allow forsubstantive periodic loading of a drug followed by prolonged drugdelivery directly into the tissue where it is needed.

In the wake of the micro-texture-creating RIGDA tooling process thepredominant visible and palpable disposition of the substrate ePTFE isthat of irregular exposed pristine crystalline villous remnantssurrounded by a very complex physical space. On gross examination, theresultant white tooling furrow course resembles a soft plowed furrow ina farmer's field. Together, the cited “texture-creating RIGDA toolingactions” create the quality topology which stimulates the in-growth offibroblasts.

Real-time and delayed inspection of the manufacturing process is enabledby a video imaging system which provides for quality controldocumentation of enlarged images 13. Two basic versions of texturedtubing may be made: “texture-out” and “texture-in” (FIGS. 5A and B).Simple inversion through the length of the tube segment is requiredafter the RIGDA tooling process is complete.

The following identifies particular components of the system: thespindle—mandrel Assembly 1; Vacuum Pump and Rotating Spindle-Mandrel arejoined at “Floating Aspiration Coupling” 17; Highly polished surfaces,Teflon and Teflon Paste Bearings and Bushings utilized, Variable SpeedDrive 2, Compound RIGDA Tooling Assembly 3 with electrical motor drivesfor tools, Micrometer Adjustable Control 14 of RIGDA Tool Position andAttitude, Intense Vacuum 18 causes adherence of ePTFE Tubing 10 toMandrel 9, Splined Mandrel 15 and Edges of Perforations 7 through wallof Mandrel along with Intense Suction, maintain adherence by increasingPurchase, Chaff Scavenge—via dedicated vacuum system 12, Video ImagingSystem 13 to document conformity with Specs., in real and delayed timeframes, as required, Electromagnetic Socket Chuck Lock 5 accurately andfirmly holds the Base Cone 6 of each Mandrel which is centered inConical Socket 22; Position of Mandrel perforations is indexed on basecone attachment—used when creating holes in blood vessel prostheses(FIG. 4A). Vacuum Loss triggers intermittent compensatory “on” cycle tomaintain critical adherence. All motion of Compound RIGDA ToolingAssembly 3 and position and attitude of RIGDA tooling 11 are madeprogrammable and micrometer adjustable, “Live Center” 20 butts ontoMandrel tip 8 for additional stabilization as required, and nitrogen gasis used to clean chaff off substrate and cutting surfaces.

In one aspect of the invention, an implantable tube for implantation ina body is provided. Preferably, it is a tube of un-sintered extrudedePTFE having a first surface and a second surface, the tube having anybeneficial porosity, the first surface being smooth and the secondsurface being textured, specifically preferably micro-textured. Thesecond surface has the beneficial effect of inducing bio-integrativescar. The texture and micro-texture is created by the “vibratory androtary impaling, gouging, distracting, tearing, releasing, avulsing andre-capturing of substrate fragments (“RIGDA tooling”) into the thicknessdimension of the tubular material, removing the fragments thereof, andleaving behind the finished tubular product. The second surface may havea furrow pattern of highly variably shaped remnant villi with whollyexposed crystalline surfaces, high fluffy regions and low regions oftroughs or channels, complex interstices and lowest regions nominallycalled wells. Optionally, the surface pattern may include plurality ofintersecting wells, structure with cross-sectional dimensions of varyingwidth. The pattern may be semi-random or uniform. Patterns, such asfurrow patterns, may be repetitive or not, and straight or optionally ina spiral. Optionally, the tube may be a laminated structure.

The second surface is arranged to stimulate a high degree of tissuein-growth, which is preferably defined as in-growth which is at least15-20 microns deep within the thickness of the micro-texture on testgrowth at three days in an appropriate laboratory animal model. Thesecond or micro-textured surface is arranged into a complexly configuredspace which acts to greatly disorder the usually orderly parallelalignment of collagen monomers and, as a consequence, effectivelydisorganizes scar tissue and softens it to some degree.

The tube thickness may be essentially uniform between the tubularorifices, or may be variable. The diameter of the tube may be uniform orvariable. Optionally, the tube wall may be perforated by at least onehole. Additionally or alternatively, the tube may be perforated bynumerous slits or lucencies cut into the substrate material by anycutting implement or a laser. The slits or lucencies in the tubularstructure manifest as pores or interstices which may contain suffusedbiologically active material which, in the implanted state, dissolves inbiologic fluid as it leaches out of the structure.

A partial short list of surgical uses for a textured ePTFE tubeincludes: (1) as a body fluid shunt for e.g. cerebrospinal fluid,controlled fistulae and others, (2) as a liner for implants inorthopedic and oral and maxillofacial surgeries to assist inbio-integration, (3) as a structure-conferring tubular implant inreconstructive surgeries of the trachea, external auditory canal, nasaland sinus passages, nasolacrimal duct, and others, (4) as a sling forstructures such as catheters, control tubes or wire leads which mayrequire body tissue fixation, (5) as a friction-reduction sleeve aroundtendons, nerves, and so forth, (6) as coronary artery, vascular andductal stent grafts, (7) as adhesive repositories for specialized cellpopulations such as stem cells, drugs, and so forth.

In one implementation, the method for fabrication may be as follows. Thetube is mounted onto a hollow mandrel, then mount the mandrel on ahollow spindle on a lathe, wherein a vacuum acts through the hollowmandrel and confers upon the resultant unitary structure a rigidrod-like shape which can be presented to a “RIGDA tooling assembly”. Thetooling action upon the material causes impaling, gouging, distractingand avulsing of areas of the substrate tubing, leaving behind a tatteredand villous substrate surface structure. This complex topology ispristine and crystalline. The convoluted villous substrate surfacetopology is extremely irregular, with extremely complex adnexal spacesthroughout the furrow patterns thus created. Optionally, the heatcreated through action of the RIGDA tooling may be cooled by liquidNitrogen spray. The particles of chaff are disposed of preferably byaspiration.

The hollow mandrel is optionally perforated by a large number ofgenerally round perforations through its wall, allowing for intensesuction adherence and purchase on the tubular substrate material. TheRIGDA tooling process includes some of, or the combined actions of,rotary impaling, gouging, distracting and avulsing, releasing,re-capturing and further avulsing of ePTFE fragments, augmented by theinduced vibration inherent in the process as described. Preferablycomputer control of machine traversal occurs, with the “RIGDA toolingassembly” moving against tubular substrate, or vice versa by moving themandrel assembly against “RIGDA tooling assembly” or by simultaneousopposing motions of both “tooling” and mandrel assemblies. The methodsmay include electromagnetically actuated conical and keyed socket chuckenabling accurate centrally aligned tooling and tubing substrate, whilepermitting a vacuum to act throughout its interior volume. The methodscreating of a given texture pattern where multiple “RIGDA tools” areemployed simultaneously and where rotary speeds, energy intensities, andmicro-texture patterns are highly variable.

The drainage cover is particularly described with reference to FIG. 7.The invented drainage cover 31 in FIG. 7 is shown in a semi-oblique viewas if placed on a flat surface, to show its essential enfoldingconfiguration around a prototypical breast implant 32 and withincompletely closed ePTFE ties 33 to show its relation to the enclosedimplant.

The drawing depicts the implant 32, reflected bi-lobed cover portions36A and 36B, ePTFE ties 33, adnexal space 34, interstitial (seroma)fluid 35, texture in grid form 45, oval/slash thru and thru cutlucencies 44 and closed drain system 39. It further shows outward facingaspect 40 of the cover, and it shows perimeters 42 of reflectedenveloping portions of the bi-lobed cover 36A and 36B joined to eachother at the implant equator by stitching, sewing, or other methods andstructures known to those skilled in the art.

The drawing also shows the implant completely enveloped by the drainagecover. The cover is shown with the textured side 40 facing away from thebreast implant, and the smooth undersurface of the cover 43 directlyfacing and contacting the implant. Labeled lucencies 44 and texturepattern 45 are shown in close proximity. The shape and distributionpattern 44 of lucencies are selected to maximize drainage coverperformance. A grid pattern represents the applied texture 45, whereasthe exemplary ovals/slashes represent the pattern of the lucencies 44shown. The invented drainage cover 31 enables effective drainage ofinterstitial fluid from the adnexal space around the implant to thecommonly used temporary suction drain 46 which is placed into intimatecontact with the cover by the surgeon.

The volume of the space between the cover and the implant (not shown) isa variable factor under the manufacturer's direct control. The surfacearea of the cover is ideally approximately 12-15% percent larger thanthe surface area of the implant, which allows for effectiveintra-operative positioning and post-operative massaging ofencapsulating scar.

The multi-lucent and micro-textured ePTFE sheet is positioned betweenthe implant and enveloping soft tissues. The sheet envelopes the implantand is bi-lobed with the opposing perimeters joined by ePTFE ligaturesat the equator of the implant. The textured surface faces outward tocontact the surrounding soft tissues and the smooth side of the covermakes contact with the implant directly.

The through and through lucencies are configured to allow for readydrainage of the immediate surrounding (adnexal) space when it is underthe influence of suction applied to the drainage system. When the skinincision is closed at surgery, the cover is pulled by suction intointimate contact with the surrounding soft tissues and also the implant.Such intimate contact makes it possible for the featured texturedsurface to induce fibroblasts to grow into and onto the convolutedfeatures of the ePTFE cover thereby beginning the process ofbio-integration. The shape and distribution of the through and throughlucencies also permits adaptive conformance of the cover to the shapeand volume of the implant. Both the pattern and shape of the lucenciesmay be regular or variable.

Bio-integration of the cover with the soft tissues is complete when thewound has completely healed. The intimate contact between all threeelements including breast tissue, cover and implant provides structuralsupport for the entire breast. The timing of non-traumatic removal ofthe suction drain is dictated by the surgeon's experience. Pleasingshape and softness are thereafter more controllable by the patient underher surgeon's direction.

The drainage cover is optionally formed as follows. It is a thinimplantable ePTFE sheet structure, the seroma drainage device preferablyhaving two different surfaces, the first surface being smooth andwherein the second surface features a micro-texture in a pattern. Asused throughout, the term ‘smooth’ relates to a surface having poresizes, depth and/or diameter of typically less than about 3 microns, andoften having pore sizes in the 1 to 2 micron range. As describedpreviously, the micro-texture is preferably comprised of very numerousshredded and torn surface villi, the micro-texture inducesbio-integrative scar. The sheet structure also manifests strategicallylocated full thickness lucencies; with the lucencies permitting the flowof biologic fluids through the structure in both directions, and whereinthe lucencies permit the sheet to be elongated along any pertinent axis.Thus, the sheet serves as a seroma drainage device in large surgicalwounds.

Any beneficial thickness, wherein both surfaces of the sheet structurefeature a micro-texture pattern which induces bio-integrative scar, suchas where the micro-texture is comprised of very numerous shredded andtorn micro-villi, and wherein the full-thickness lucencies permit theflow of biologic fluids through the structure in both directions; andwherein the lucencies permit the sheet to be elongated along anypertinent axis. Preferably the texture is a “micro-texture” whichinduces scar and serves functionally to bio-integrate with surroundingsoft tissue. Preferably, the opposing side is smooth, preventing scarinduction or attachment.

When used as a drainage cover for breast implants, the textured sidefeatures the micro-texture created using the method generally describedherein wherein the sheet is accommodated using a unique mandrel with alarge diameter to suit and wherein the opposing side of the sheet issmooth or non-textured. The textured surface of the cover faces awayfrom the implant and toward surrounding soft tissues, and the smoothside of the cover faces toward the implant, yet remains totallyun-attached to the implant surface.

Preferably the cover includes through and through cut lucencies tofacilitate the sheet stretching along any pertinent axis of elongation,thus permitting adaptive conformance to implant shape and volume. Thisfeature allows for the ingress and egress of biologic fluids into thespace between the implant and the cover, thereby enabling goodpostoperative drainage of seroma fluid over a protracted period of timeunder the influence of wound suction.

The drainage cover is preferably constructed so that it comprises twolobes of a sheet structure wherein all of the opposing perimeters arejoined with filaments of like material under moderate tension, and withthe outward facing surface being micro-textured and all of the inwardfacing surface being substantively smooth or non-textured. The drainagecover may be constructed so that duplicate copies of either or bothportions of the corresponding bi-lobed sheet are joined at theircorresponding peripheries to enhance the performance of such thickerdrainage cover.

The drainage cover may have the texture pattern consisting of parallelor intersecting furrows wherein the cut lucencies are located within theborders of texture furrows. The texture furrows may consist of tatteredand shredded surface villi of ePTFE whose function is to inducebio-integrative scar and where the hyper-convoluted micro-topographydisorganizes the induced scar.

It will be readily apparent to those of ordinary skill in the art inlight of the teachings herein that certain changes and modifications maybe made thereto without departing from the spirit or scope of theappended claims. For example, while often described with specificreference to tubes, the texturizing tooling and methods may be used totexturize and structure, such as films, sheets and three dimensionalstructures. Implantable textured ePTFE tubes and other structures can beengineered to have a wide variety of attributes and functions.Variations of the above-described methods of manufacture ofmicro-textured tubular ePTFE which are based upon RIGDA tooling andremoving of substrate material will be appreciated by those skilled inthe art. The salient features of the described sheet-like drainage coverwork together to improve upon the prior art. Certain variations andmodifications of the preferred embodiment will be apparent to those ofordinary skill in the art. Accordingly, the claims herein should beinterpreted as broadly as possible. It is therefore expected that thescope and spirit of the claims in light of the teachings of theinvention, be interpreted liberally to include all variations andmodifications.

I claim:
 1. A method for texturizing an implantable tube forimplantation in a body, the tube being an extruded ePTFE tube, the tubehaving a first inner surface and a second outer surface, the tube havinga thickness dimension between the first inner surface and the secondouter surface, the second outer surface being textured to promote bodytissue bio-integration into the second surface, the second outer surfacebeing textured by the process comprising the steps of: providing amandrel sized to receive the inner surface of the tube, the mandrelhaving a plurality of holes to couple the inner surface of the tube to avacuum space, releasably affixing the first inner surface to the mandrelby application of a vacuum to the vacuum space, contacting an activerotary gouge to the second outer surface to remove material from thetube, at least including gouging material in the thickness dimensionfrom the second surface toward the first surface, thereby separating thegouged material from the tube, thereby forming an irregularly configuredsecond outer surface, the outer surface having resultant irregularvoids, removing the gouged material from the textured second surface,moving the rotary gouge and mandrel relative to one another, anddiscontinuing application of the vacuum and removing the texturized tubefrom the mandrel.
 2. The method for texturizing an implantable tube ofclaim 1 wherein the mandrel rotates around an axis of the tube.
 3. Themethod for texturizing an implantable tube of claim 1 wherein the rotarygouge moves parallel to the axis of the tube.
 4. The method fortexturizing an implantable tube of claim 1 wherein the rotary gougemoves at a non-zero angle relative to the axis of the tube.
 5. Themethod for texturizing an implantable tube of claim 1 wherein multipleactive rotary gouges contact the tube.
 6. The method for texturizing animplantable tube of claim 1 wherein the mandrel is hollow.